The Australian Medical Association (AMA) has distanced itself from a group of prominent doctors who say children are better off when raised by heterosexual parents, rather than same-sex couples.

Around 150 medical practitioners from the group Doctors for the Family, including a member of Victoria's Human Rights and Equal Opportunity Commission, say children raised in heterosexual relationships "do better in all parameters".

The group has signed a submission to the Senate inquiry into marriage equality, opposing same-sex marriage and asserting that marriage between a man and a woman is the "basis for a healthy society".

The submission says that marriage, as it is currently defined under the Marriage Act 2004, is more stable than same-sex marriages.

Doctors for the Family's convener Lachlan Dunjey, a right-to-life campaigner who has run as a Senate candidate for the Christian Democratic Party, told ABC News Radio the group is concerned about the health consequences for children of gay marriages.

There is a growing body of evidence that says there's no difference in [a child's] psychological development, their general health, their sexual orientation.

AMA president Steve Hambleton

"It's well proven that children who grow up with a mother and a father in a biological mother-and-father family do better than children who don't have the opportunity to grow up in that kind of family," he said.

But AMA president Steve Hambleton has rejected the claims, saying there is no evidence that children with same-sex parents are any different to those with heterosexual parents.

"There is a growing body of evidence that says there's no difference in their psychological development, their general health, their sexual orientation," he said.

Dr Hambleton says the opinions expressed in the submission do not reflect the views of the wider medical community, saying there are nearly 90,000 doctors in Australia.

He says doctors must be mindful of putting their opinions forward because they hold influential positions in society.

"That's part of the reason why it's a bit disturbing that these opinions have been proffered. It's certainly not the opinion of the AMA body of doctors," he said.

Doctors for the Family's submission references a 2011 report "For Kids' Sake", which was commissioned by the Australian Christian Lobby and authored by University of Sydney law professor Partick Parkinson.

Who are Doctors for the Family?

Doctors for the Family was established in November 2011.

Its convenor is Dr Lachlan Dunjey.

Dr Dunjey is a Perth GP and a right-to-life campaigner who has run as a Senate candidate for the Christian Democratic Party in multiple elections.

He was president of Baptist Churches of WA in 1989/90 and set up Medicine With Morality in 2006 to lobby politicians on issues including cloning and euthanasia.

Doctors for the Family says it aims to "highlight the health aspects of marriage and family and ensure a healthy future for our children".

Greens Senator Sarah Hanson-Young has dismissed the submission and says discrimination within the Marriage Act should end.

"A child being brought up in a loving home is far more important - and that quality of parenting is far more important - than any of the criticisms that have been waged by this group of individuals," she said.

"I think that's one of the more ridiculous propositions that's ever been put in Australian public debate. I don't know who these doctors are but it certainly doesn't accord with every other piece of research that's out there on this issue," he said.

Immediate explanation

Meanwhile, Victoria's Deputy Chief Psychiatrist, Professor Kuravilla George, who was appointed to the board of the Human Rights and Equal Opportunity Commission by the State Government, is one of the doctors who signed the petition.

Victoria's Mental Health Minister is seeking an urgent explanation from the state's Chief Psychiatrist, Ruth Vine, over her deputy's decision to join forces with Doctors For The Family.

A spokesman for Victoria's Mental Health Minister, Mary Wooldridge, says the Government was unaware of the submission and is seeking an immediate explanation.

Professor George has declined the ABC's request for an interview but confirmed his involvement with the group.